Question

o oitavo termo da PG ( -5,-10,-20)é?

Answer 1

$a_{n}$ = $a_{1}. q^{(n-1)}$

$a_{8}$ = $(-5).2^{(8-1)}$

$a_{8} = (-5). 2^{7}$

$a_{8} = (-5).128$

$a_8 = -640$